In general, a centrifuge or a centrifugal filter is an apparatus for separating, refining and concentrating a substance having a particular composition or specific gravity using centrifugal force. The centrifuge is used for filtering impurities from oil (lubricant or fuel) used in engines or a variety of machines.
FIG. 1 is a cross-sectional view showing the structure of a centrifuge of the related art.
The centrifuge shown in FIG. 1 is used for filtering impurities from oil used in engines.
The centrifuge includes a shaft 10, a rotor 20, a stand tube 30 and a casing 40. The shaft 10 has defined therein a flow path through which oil is introduced. The rotor 20 is configured to rotate about the shaft 10. The stand tube 30 is configured to rotate about the shaft 10 together with the rotor 20, and sprays oil introduced through the shaft into the rotor. The casing 40 has an oil inlet and an oil outlet, and houses the rotor 20 therein to receive oil sprayed from a nozzle 21 of the rotor 20.
The centrifuge is configured to receive oil circulated by the actuation of a pump (not shown) and subsequently filter a variety of impurities from oil using centrifugal force. More specifically, the rotor filters impurities while rotating at a high speed based on reaction principle in response to oil being sprayed through the nozzle of the rotor.
Although this centrifuge can separate and remove impurities from oil, it cannot remove moisture. Therefore, when an oil filtering system is constructed using a centrifuge, a skimmer is added in order to remove moisture from oil.
FIG. 2 is a cross-sectional view showing the structure of another centrifuge of the related art.
The centrifuge shown in FIG. 2 is configured to remove impurities as well as moisture from oil. While a rotor 50 is rotating, impurities A and moisture B move to the inner circumference and are subsequently separated from oil by centrifugal force. Moisture B separated from oil is discharged through a flow path 51 provided inside the rotor. When a preset amount of impurities A is accumulated in the inner circumference of the rotor 50, an impurity outlet 52 is opened to discharge impurities A out of the rotor 50.
As described above, this centrifuge can advantageously remove moisture from oil without using a skimmer. However, there is a contradictory problem in that water must be added in order to separate moisture or remove impurities. This also increases the contact area between water and oil, thereby creating an emulsion.